DE102014102203A1 - Method for transporting plastic preforms, device for transporting plastic preforms and circuit arrangement for such a device - Google Patents

Abstract

The invention relates to a method for transporting plastic preforms, wherein the plastic preforms are fed by means of a feed device to a transport device and the transport device comprises a first roller body and a second roller body, which extend substantially parallel to each other and the plastic preform is transported between these Rollenkörperm, wherein a Section of the plastic preforms is supported by both roller bodies and wherein a further portion of the plastic preforms passes between the roller bodies. According to the invention, by means of a first measuring device, at least one first characteristic value for a covering state of the plastic preforms is detected and a second characteristic value for the occupation state of the plastic preforms is detected by means of a second measuring device, which is located in the transport direction of the plastic preforms after the first measuring device Based on both values at least one manipulated variable of the feeder or the transport device is controlled.

Description

The present invention relates to a method and apparatus for transporting plastic preforms. Such devices have been known for a long time from the prior art. It is known that the plastic preforms are first heated by means of a furnace and then fed, for example, a blow molding machine, which blows these plastic preforms to plastic containers.

These devices for transporting plastic preforms are often constructed in multiple stages. Thus, feed devices can be provided which feed the plastic preforms to a sorting device, for example a so-called roller sorter. In such a roller sorter, conveyor belts or feed devices for the plastic preforms run at a fixed parameterized speed in the prior art. The respective speed is firmly stored for a size of the plastic preforms. Thus, such a roller sorter regulates depending on the length of a sorting line with 3 to 4 different speeds. For this type of control, several, for example, 3 to 4 light barriers are normally used or needed.

Currently, however, the problem arises in the prior art that setting these parameters for the various speeds is very time consuming. In particular, deviations may occur in the course of operation which thus lead to problems in the case of a fixed parameterization. For example, it is possible that during the course of a working day the room temperature changes and thus also the physical condition of the plastic preforms. These can then, for example, more or less stick. In this case, however, the parameters must always be readjusted. However, the prior art only causes a control, which can also lead to failures.

It is therefore an object of the present invention to provide a method and a device which enable a more flexible reaction to such fluctuations, for example daily variations. These objects are achieved according to the invention by the subject matters of the independent patent claims. Advantageous embodiments and further developments are the subject of the dependent claims.

In a method according to the invention for transporting plastic preforms, the plastic preforms are fed to a transport device by means of a feed device and the transport device has a first roller body and a second roller body which extend substantially parallel to one another, the plastic preform being transported between these rollers and a section the plastic preforms are supported by both rollers and wherein a further portion of the plastic preforms passes between the rollers (in particular by a gap formed between the rollers).

According to the invention, by means of a first measuring device, at least one first characteristic value for an occupancy state of the plastic preforms or an occupation state of the device with the plastic preforms is detected and a second for the occupation state by means of a second measuring device, which is in the transport direction of the plastic preforms after the first measuring device the plastic preforms or an occupation state of the device with the plastic preforms characteristic value detected and it is controlled on the basis of both values at least one manipulated variable of the feeder or the transport device.

In particular, a regulation of said manipulated variable of the feed device or the transport device takes place. Preferably, the characteristic value is detected continuously by means of at least one measuring device and preferably by means of two measuring devices and these values are taken into account in each case in the regulation of the respective manipulated variable.

Advantageously, the characteristic value is, for example, a number of plastic preforms in a specific area covered by the measuring device or also a number of those plastic preforms which pass this area over a certain period of time. Thus, for example by means of a measuring device within a predetermined interval, the number of events are counted, which are characteristic, for example, of the occurrence of plastic preforms.

In a further advantageous embodiment, the device also has a discharge device, which ejects faulty or incorrectly positioned plastic preforms. Thus, it may be possible, for example, that plastic preforms are not transported in a conventional hanging position between the rollers, but, for example, lying. In this case, they can be detected by the discharge device and discharged from the transport process.

Advantageously, an area of the plastic preforms, in particular a support ring, is supported between the two rollers and another area of the plastic preforms, such as a base body, lies or penetrates a gap which is formed between the two rollers.

It is therefore proposed according to the invention that a regulation of at least the feed device or the transport device is carried out taking into account both measured values of the two measuring devices. In this way, it is possible to respond both to creeping or long-term changes as well as to short-term fluctuations, for example in the dosage.

In an advantageous method, at least one manipulated variable of the feed device is controlled on the basis of both of said values. Preferably, the manipulated variable of the transport device is controlled only on the basis of or taking into account one of the two measured values.

The manipulated variable of the feed device can be, for example, a feed rate at which the plastic preforms are fed by the feed device to the transport device, such as the speed of the abovementioned conveyor belts which feed the plastic preforms.

Advantageously, at least one manipulated variable of the transport device is selected from a group of manipulated variables, which comprises a rotational speed of at least one roller body and preferably both roller body, an inclination of the roller body, a distance between the roller body, a parallelism of the roller body or a segmentation of the roller body. These parameters or parameters have an effect on the transport speed of the plastic preforms.

Thus, for example, by a variation of the rotational speed of the roller body and the movement speed of the plastic preforms can be influenced. Also, by changing the distance between the roller bodies, it is possible to change the transport speed, as is regulated by this distance, with which areas of the plastic preform or its support ring rests on the two rollers. In addition, it would also be possible that a plurality of roller bodies are arranged one behind the other, which can rotate at different speeds. Also, an inclination of the roller bodies in their entirety or even an inclination of individual segments (also with respect to each other) can be changed.

In a further advantageous embodiment, at least one measuring device detects the measured value without contact. In particular, at least one measuring device is an optically detecting measuring device, and particularly preferably this measuring device is selected from a group of measuring devices which include light barriers, camera systems and the like.

In a further advantageous method, the manipulated variables are regulated by means of at least two control devices. In this case, the entire control is preferably carried out in at least two stages. It is conceivable that a first stage compensates for creeping or long-term changes in the environment. This first stage may be an averaging controller, such as a PI controller. In each case, this controller can respond to a desired value of a movement speed as a function of a multiplicity of measured values and in this way compensate for slow changes.

In a further stage, it may be a regulation which responds to short-term fluctuations, in particular short-term fluctuations in the dosage and which as a control target brings about a constant stagnation point, in particular in the area of a measuring device. This may be, for example, a P-controller.

As mentioned above, both regulations affect both the first and the second manipulated variable. The first manipulated variable may refer to the metering unit, such as a high-level conveyor and connected feed belts. The second control unit or controlled variable may relate to a storage area or a storage unit and thus to an adaptation of the respective roller movements. Preferably, therefore, a cascaded control is used.

It is conceivable that one of these regulations, in particular that which is intended for rapid regulation (catch-up controller) for both controls or both manipulated variables, responds to the same output signal from the system and in particular to an output signal of the second measuring device mentioned above. This same signal can also be used for the second controller, an averaging controller, or for two averaging controllers.

In addition, however, this second control device can also be adapted via a second output signal, namely that of the first measuring device. This results in a favorable ratio between the catch-up and the dosing unit. Advantageously, it is possible that the two control variables regulated in separate control circuits become. However, it is also possible that at least one of these control circuits and preferably both control circuits have two control devices connected in series, wherein preferably an output signal of the first control device is supplied to the second control device.

Preferably, a control device in its entirety will therefore react to the mechanical properties of the system and can preferably also be adapted to it. So it is possible that during a set-up operation, a certain ratio is learned and can be automatically responded to slow changes in the course of operation.

Preferably, an evaluation of at least one control device can also take place, for example a control device which controls the transport device and in particular the rollers. By this evaluation, a quantitative comparison basis for different properties of the rollers or different properties of the transport device can be created. By this evaluation, it is possible that at least one control device is also used as a measuring system for sliding and friction properties of the rollers.

The invention thus proposes a self-learning control for a sorting of plastic preforms, which preferably adapts independently to the changing conditions. In this case, for example, by means of an optical sensor, a measurement of a degree of occupancy can be measured at a feeder, also a count of plastic preforms can be made on a feed belt, for example by means of a 3D detection. In addition, however, a count of the plastic preforms on the feed belt would be possible, for example by a pulse evaluation falling plastic preforms approximately by means of acoustics or pressure-sensitive plates. Furthermore, in a preferred method, a presorting and / or centering of the plastic preforms with the feed device, for example by means of a feed belt, made.

Preferably, values recorded by the measuring devices are stored at least temporarily. These stored measured values can preferably also serve as reference values for the control. In a further preferred method, output values are fed to a control device of a further control device. Particularly preferably, output signals or output values of a PI controller, in particular of a PI controller functioning as a mean value regulator, are supplied to a P regulator, in particular to a P controller acting as a catch-up controller.

In a further preferred method, the device has a return belt, which can be used particularly preferably by using gaps in the feed belt to connect this return belt.

Advantageously, a degree of occupancy is added to this feed belt by means of a further measuring device.

In a further advantageous method, an automatic tracking of the control parameters takes place as a function of an ambient value, such as a temperature value or a humidity value. This can be done both in the roles and in the feed belt or a possible return belt.

In a further advantageous embodiment, at least one ambient value is thereby measured, in particular a temperature value or a moisture value.

Preferably, an independent tracking of the controlled variables takes place with an independent learning function.

In a further advantageous method, no more controllable states are detected and initiated in response to such non-controllable conditions measures, such as an emergency stop, ejection of plastic preforms or the like. Thus, for example, split roller segments may be provided, which allow ejection of individual plastic preforms in case of error or need.

The individual rollers or roller segments can be made to slide, but it would also be possible that they are driven by a predetermined contour, such as a scale or helical contour.

As mentioned above, a change in the parallelism of the two roles can take place to each other, which may for example depend on the Vortriebbedarf. For this purpose, it is possible that the rollers or at least one roller are arranged on slidable carriages. Preferably, however, the two rollers are moved symmetrically to each other. In this way, the actual transport path of the plastic preforms can be maintained, which is particularly useful in terms of downstream transport facilities, such as transport stars, transport rails preferably with air support and the like.

In addition, it would also be possible, as mentioned above, to change the pitch of the roller segments, which also depends on one Propulsion requirement can be made. In addition, the number of rollers or the number of segments could also be changed, whereby a further drive coupling could also be used. For example, adjoining friction rollers could be provided, which at the same time could also assume support in the direction of an imbalance.

In this way, it is possible that the system adapts to the influences of the environment and / or the quality of the objects to be sorted and thus the performance is improved compared to today's systems.

In a further advantageous method, at least one of said control devices is an averager or a catch-up controller. As mentioned above, these control devices are advantageously connected in series. Advantageously, an output value of the mean value regulator is fed to a catch-up controller.

The present invention is further directed to a device for transporting plastic preforms. This device has a feed device, as well as one of these feed device in a transport direction of the plastic preforms downstream transport device, wherein the feed device, the plastic preforms of the transport device and wherein this transport means comprises a first roller body and a second roller body, which extend substantially parallel to each other and wherein the / the plastic preforms can be transported between these roller bodies or are.

According to the invention, the device has a first measuring device, which detects at least a first value characteristic of an occupancy state of the device with the plastic preforms and a second measuring device, which is located in the transport device of the plastic preforms after the first measuring device and which second for the occupation state of the device recorded characteristic value with the plastic preforms. Furthermore, the device has a control device which, based on both values, controls and in particular regulates at least one manipulated variable of the feed device or the transport device.

It is therefore also proposed on the device side that occupancy states are detected by means of two measuring devices positioned at different locations, such as light barriers or camera systems, and at least one of the two manipulated variables is changed or a drive of the feed device or the transport device is controlled on the basis of these measured values.

The drive of the transport device may be, for example, an electric motor which causes the rotation of one or both rollers.

The present invention is further directed to a circuit arrangement for controlling a device for transporting containers and in particular a device of the type described above. This circuit arrangement has a first controllable drive device, which causes the containers to be fed to a transport device, and a second controllable drive device, which influences the transport of the containers by means of the transport device. Furthermore, the circuit arrangement has a first measuring device, which detects at least one value characteristic of an occupancy state of the device with the containers, and a second measuring device, which is located in the transport direction of the plastic preforms after the first measuring device and which has a second for the occupancy state of the device the value characteristic of the containers.

According to the invention, the circuit arrangement has a first control device, which has a control input, via which the first control device, a signal of the second measuring device can be supplied and a second control device, which also has a control input, via which the second control device, a signal of the first measuring device can be fed and wherein an output signal of the second control device of the first controllable drive device can be fed.

Under the respective Zuführbarkeit is understood in particular that line connections or wireless connections exist, which transmit the respective signals or variables from the measuring devices to the control device.

In the drive device, which causes the supply of the containers to a transport device, it may be, for example, a drive motor which drives a feed belt. In the drive device, which influences the transport of the containers by means of the transport device, it may be, for example, a motor that drives the above-mentioned roles. However, it could also be a drive device, by means of which, for example, an inclination of the rollers can be changed or with which a parallelism of the two rollers or the like can be changed.

Thus, it is proposed here that at least two control devices are provided, which control or regulate the first drive device. The above-mentioned signals are - as mentioned above - characteristic of the occupancy states with the containers and in each case also represent the inputs of the control devices or, if appropriate, are fed or added together with further signals to the control device.

As mentioned above, the containers are in particular plastic preforms. However, the circuit arrangement can also be carried out for other types of containers, for example for plastic bottles, for glass bottles, for beverage cans, for container closures, beverage crates and the like. In addition, the circuit arrangement can also be made available for systems which effect, for example, a packaging or palletizing of containers.

Advantageously, the second control device of the first control device is connected downstream, and preferably an output signal of the first control device of the second control device is thus supplied. Thus, the circuit arrangement is particularly preferably constructed such that both control devices are integrated in the same control loop and are preferably connected in series in this control loop.

The first control device is preferably a PI controller and / or the second control device is a P controller. The PI controller preferably has a high I component, which relates in particular to the production speed of the machine to be supplied. This is preferably in a range between 50 and 1,000 machine cycles.

In a further advantageous embodiment, the circuit arrangement has a further control circuit for the second drive device. This second control circuit preferably also has two serial control devices. Advantageously, the first control loop and the second control loop are designed in parallel with respect to the control devices. In a further advantageous refinement, the measuring signal of the second measuring device can be fed twice to at least one control loop, and in particular to both a first and a second control device of this second control loop.

In a further advantageous embodiment, at least one control device and preferably the first control device also has an input, via which this control device, a signal of the first measuring device can be fed. Thus, in this embodiment of a control device, both the signal of the first measuring device and the signal of the second measuring device can be supplied. Preferably, the circuit arrangement has two control circuits, wherein these two control circuits preferably each have at least two control devices arranged in series. Preferably, however, one control device of both control circuits is supplied with a value or a measurement signal of the second measuring device.

Further advantages and embodiments will be apparent from the attached drawings:

Show:

1 an illustration of an apparatus for transporting plastic preforms;

2 a schematic representation of a device according to the invention in a first embodiment;

3 a representation of a device according to the invention in a second embodiment;

4 a detailed view illustrating a role division; and

5 a schematic representation of a circuit arrangement for controlling such a device.

1 shows an illustration of an apparatus for transporting plastic preforms. The reference number 2 refers to a feeding device for feeding the plastic preforms. This feeder has an ascending conveyor 22 on, over which the plastic preforms are fed to a collecting container. From this feeder 2 arrive the plastic preforms on the transport device 4 from which she is in the 1 be promoted obliquely down. This device according to the prior art in this case has a plurality of light barriers to control the transport of the plastic preforms.

2 shows a schematic representation of a device according to the invention 1 for transporting plastic preforms 10 , These plastic preforms 10 have a support ring 10a on, which has a larger cross-section than a subsequent body 10b , In this way, the plastic preforms between two roller bodies 42 and 44 (the latter not shown) are transported. These two reel bodies 42 . 44 be from at least one drive device 14 driven and during transport so the plastic preforms can slide down along these roles.

The reference number 12 indicates a drive device, which the supply of Plastic blanks can control, for example, by controlling a feed rate.

The reference number 16 indicates an ejector which serves to eject misoriented plastic preforms. This can be an ejection device which comes into contact with misoriented plastic preforms and can eject them from the transport path. The reference symbol P denotes a transport direction of the plastic preforms to be sorted or to be transported 10 ,

The reference number 6 indicates a first measuring device, which determines an occupancy state with plastic preforms in a certain area of the transport path. This device can be, for example, a light barrier device which can determine how many plastic preforms - in particular per unit of time - pass through this first measuring device.

The reference number 8th indicates a second measuring device, which is a stagnation point light barrier here. Here, too, this light barrier can measure the occupancy state, this taking place downstream of the first measuring device. The first measuring device is thus a dosing photocell.

At the in 3 In the embodiment shown, the first measuring device is not along the transport device 4 arranged but in an area of the feeder 2 , This can be, for example, a camera which can output an image which is representative of the number of plastic preforms in the area of the feed device. Depending on the two signals of these two measuring devices 6 and 8th the device is controlled and in particular both the drive device 12 as well as the drive device 14 controlled.

4 shows a possible embodiment of a control of the movement sequence. In this embodiment is a role 42 divided into two roller segments, which of different drive devices 14a . 14b are driven. In particular, a different speed drive these segments is 42a . 42b possible. Also in this way, the transport speed of the plastic preforms can be controlled at least in sections.

5 shows a representation of a switching arrangement 60 for controlling the device. This switching arrangement again has the above-mentioned device 1 on, wherein schematically also the two drive means 12 and 14 are shown. There are two control circuits next to it 70 and 90 recognizable. The control loop 70 serves to drive the first drive means 12 and the control loop 90 serves to control the drive device 14 ,

The control loop 70 has a first control device 62 and a second control device 72 on. The first controller is an averaging controller used to compensate for creeping changes. The second control device 72 is designed as a catch-up controller, which can respond to short-term fluctuations, for example in the dosage. Accordingly, the first control device 62 both the measuring signals S1 of the first measuring device and the measuring signals S2 of the second measuring device 8th fed. For this purpose, the inputs 78 and 74 intended. The signals can be connected or added serially. An output signal of the first control device is the second control device 72 supplied, wherein additionally the measuring signal S2 is again supplied to the second measuring device. On the basis of these signals, in turn, with an output of the second control device 72 the drive device 12 controlled.

The second control circuit 90 has a first control device 82 and a second control device 92 on. Here are both the first control device 82 as well as the second control device 92 only the measuring signals of the first measuring device 6 fed. This is also useful insofar as the second drive device 14 the first drive device 12 is downstream and the second drive means, such as a drive for the rollers, not on short-term fluctuations, which in particular also of the measuring device 6 can be detected, react. This is the second loop 90 but not dependent on an output signal of the first measuring device 6 ,

However, it would also be conceivable to have a uniform or a common control device which performs both the tasks of the first control device 72 as well as those of the second control device 92 to provide for.

The Applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are novel individually or in combination with respect to the prior art.

LIST OF REFERENCE NUMBERS

P

transport direction

S1, S2

measuring signal

2

feeding

4

transport means

6

first measuring device

8th

second measuring device

10

The plastic preforms

10a

support ring

10b

body

12

driving means

14

driving means

16

ejection means

22

ascending conveyors

42

role

42a

segment

42b

segment

44

role

62

first control device

70

loop

72

second control device

74, 78

entrance

82

first control device

90

loop

92

second control device

Claims (10)

Method for transporting plastic preforms, wherein the plastic preforms ( 10 ) by means of a feeder ( 2 ) a transport device ( 4 ) and the transport device ( 4 ) a first roll body ( 42 ) and a second roll body ( 44 ) which extend substantially parallel to each other and the plastic preform is transported between these rollers, wherein a portion ( 10a ) of the plastic preforms ( 10 ) is supported by both rollers and wherein a further section of the plastic preforms ( 10 ) between the reel bodies ( 42 . 44 ) characterized in that by means of a first measuring device ( 6 ) at least one first for an occupancy state of the plastic preforms ( 10 ) characteristic value is detected and by means of a second measuring device ( 8th ), which in the transport direction (P) of the plastic preforms after the first measuring device ( 8th ), a second characteristic value for the occupation state of the plastic preforms is detected and, on the basis of both values, at least one manipulated variable of the feed device or the transport device is controlled. A method according to claim 1, characterized in that at least one manipulated variable of the feed device ( 2 ) is controlled on the basis of both values. Method according to at least one of the preceding claims, characterized in that at least one manipulated variable of the transport device ( 4 ) is selected from a group of manipulated variables which determines a rotational speed of the roller bodies ( 42 . 44 ), an inclination of the reel body ( 42 . 44 ) a distance of the roller body ( 42 . 44 ), a parallelism of the reel body ( 42 . 44 ) or a segmentation of the roller bodies ( 42 . 44 ). Method according to at least one of the preceding claims, characterized in that at least one measuring device detects the value without contact. Method according to at least one of the preceding claims, characterized in that the manipulated variables are regulated by means of at least two control devices. A method according to claim 5, characterized in that at least one control device is a P-controller or a PI controller. A method according to claim 6, characterized in that output values of the PI controller are supplied to the catch-up controller. Contraption ( 1 ) for transporting plastic preforms with a feed device ( 2 ) and one of these feeding devices in a transport direction of the plastic preforms ( 10 ) downstream transport device ( 4 ), wherein the feed device, the plastic preforms ( 10 ) of the transport device ( 4 ) and wherein said transport means comprises a first reel body ( 42 ) and a second roll body ( 44 ), which extend substantially parallel to one another and the plastic preform can be transported between these rollers, characterized in that the device comprises a first measuring device ( 6 ), which detects at least a first value characteristic of an occupancy state of the device with the plastic preforms and a second measuring device ( 8th ), Which in the transport direction (P) of the plastic preforms after the first measuring device ( 8th ) and which detects a second characteristic value for the occupation state of the device with the plastic preforms, and a control device which, on the basis of both values, detects at least one manipulated variable of the feed device ( 2 ) or the transport device ( 4 ) controls. Circuit arrangement ( 60 ) for controlling a device ( 1 ) for transporting containers ( 10 ) with a first controllable drive device ( 12 ) which supply the containers to a transport device ( 4 ), with a second controllable drive device ( 14 ) which influences the transport of the containers by means of the transport device with a first measuring device ( 6 ) which at least one first for an occupancy state of the device ( 1 ) with the containers ( 10 ) characteristic value and with a second measuring device ( 8th ), which in the transport direction (P) of the containers ( 10 ) after the first measuring device ( 6 ) and which a second for the occupancy state of the device with the containers ( 10 ) characteristic value is characterized in that the circuit arrangement ( 60 ) a first control device ( 62 ), which has a control input ( 74 ), over which of the first control device ( 62 ) a signal (S1) of the second measuring device ( 8th ) can be fed and a second control device ( 72 ), which also has a control input ( 76 ), via which the second control device ( 72 ) a signal (S2) of the second measuring device ( 8th ) can be fed and wherein an output signal of the second control device ( 72 ) of the first controllable drive device ( 12 ) can be fed. Circuit arrangement according to Claim 9, characterized in that at least one regulating device ( 62 ) also has an entrance ( 78 ), via which this control device also a signal of the first measuring device ( 8th ) can be fed.

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